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Articles

Heterosis in the lactation curves of Girolando cows with emphasis on variations of the individual curves

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Pages 85-95 | Received 04 May 2018, Accepted 21 Jan 2019, Published online: 05 Feb 2019

Figures & data

Table 1. Number of cows, herds and test day milk yield records as well as 305-day milk yield records (TMY) of genetic groups with different proportion of Holstein genes obtained from the Brazilian databases.

Figure 1. Trajectory of lactation curves estimated by 305-day milk yield from database (TMY), Wood’s linear model (WDlin), Ali and Schaeffer’s model (ASH), Wood’s nonlinear model (WDnlin) and Wilmink model (WL) for 1/2H (A), 1/4H (B), 3/4H (C), 3/8H (D), 5/8H (E), 7/8H (F), G (G) and H (H) genetic groups.

Table 2. Estimated parameters (mean ± SE) of the lactation curve obtained from different nonlinear models, adjusted coefficient of determination (R 2 Adj), root mean square error (RMSE) and Akaike information criterion (AIC).

Table 3. Estimated parameters (mean ± SE) of the lactation curve obtained from different linear models, adjusted coefficient of determination (R2 Adj), root mean square error (RMSE) and Akaike information criterion (AIC).

Table 4. Estimated (mean ± SE) of peak yield (PY), peak time (PT), persistency (P2:1; P3:1, P3:2 and Pweller) and 305-day milk yield (TMY) for different genetic groups estimated by nonlinear models.

Table 5. Estimated (mean ± SE) of peak yield (PY), peak time (PT), persistency (P2:1; P3:1, P3:2 and Pweller) and 305-day milk yield (TMY) for different genetic groups estimated by linear models.

Table 6. Heterosis effect (mean ± SE) for Wilmink parameters (‘a’, ‘b’ and ‘c’), peak yield (PY), peak time (PT), persistency measures (P2:1, P3:1, and P3:2) and 305-day milk yield (TMY) estimated Wilmink nonlinear model.